Boost Metabolism and Prevent Middle-Age Weight Gain

Surprising new ways to reverse middle-aged spread

You diet more than ever, but don't weigh less. Exercise regularly, but still feel flabby. And your once perfectly fitting clothes now seem snug.

If you're nodding your head in agreement, chances are you're in the over-35 club. Like most members, you probably have a stay-slim formula (something like regular walks plus no ice cream at night) that no longer seems to be working.

"If you never had problems losing or maintaining your weight in your 20s or even in your early 30s, you may not be ready for what happens next," warns Madelyn H. Fernstrom, Ph.D., director of the Weight Management Center at the University of Pittsburgh Medical Center. "Your metabolism slows by 5 percent each decade. Compared to age 25, you'll burn about 100 fewer calories a day at 35 and 200 fewer at 45. Do nothing, and you could gain eight to 12 pounds a year."

With age, muscle mass diminishes and so does your metabolic rate (the number of calories your body burns throughout the day, whether you're sleeping, sitting, or sprinting to catch a bus). Making matters worse, many women unwittingly sabotage their calorie-burning potential with crash diets, ineffective exercise strategies, and other metabolism-busting habits.

Don't fret yet. Although there are no magic bullets, there's plenty you can do to boost the number of calories your body burns every day and thus maintain or even lose weight. Here, the six biggest mistakes you can make — and the research-proven metabolism fixes.

Mistake: Relying on Just Your Scale

The basic ones, which only calculate pounds, can't tell you what percentage of your body weight is lean, calorie-burning muscle and how much is puffy, sluggish fat. "Even a woman whose weight is in the normal range can have a high percentage of body fat and a low percentage of muscle," Fernstrom says. "And the less muscle you have, the fewer calories you'll burn."

The metabolic difference between a pound of muscle and a pound of fat is dramatic: Muscle burns at least three times more calories. "A woman who weighs 130 pounds and has a healthy 25 percent body fat will burn about 200 more calories per day than a 130-pound woman with about 40 percent body fat — a typical level for women at midlife," says David C. Nieman, Dr.P.H., director of the Human Performance Laboratory at Appalachian State University in Boone, NC. "If the woman with more body fat doesn't start modifying her diet or increase her exercise, she could start putting on weight really fast."

The Fix: Get an Expert to Weigh In

Visit your local gym (or a fitness center affiliated with a hospital) and ask for a body-fat reading. "Find out whether the person who measures you has been trained," advises Fernstrom. People who have been certified by the American College of Sports Medicine or who are exercise physiologists should have training in body-fat analysis. A good way to check their accuracy: "At your first visit, get two measurements within minutes of each other by the same person to see how much variation there is. A little, like 2 to 3 percent, is OK," says Fernstrom. To track your progress, get rechecked roughly every three months.

You can eyeball your fat level at home, too. "If you've got a poochy tummy or can pinch an inch or more of fat at your waistline or upper arm, you're probably carrying more body fat than you should," Fernstrom notes.

"Anything over 30 percent should be a wake-up call to make some real changes," she adds.

Mistake: Crash Dieting

When you slash too many calories, you send your body into starvation mode. "A flat-out fast will drop the average woman's metabolic rate by at least 25 percent," says Nieman. "If you're on a very-low-cal regimen, in the 400- to 800-calorie range, it falls by 15 to 20 percent." Eating fewer than 900 calories a day also prompts your body to burn desirable muscle tissue as well as fat, which slows your metabolic rate even more.

The Fix: Shed Pounds S-L-O-W-L-Y

"If you stay within the 1,200- to 1,500-calorie range, you can still slim down — and you'll lower your metabolic rate only by about 5 percent," explains Nieman. "What's more, about 90 percent of the weight you lose will be fat."

Regardless of which type of diet plan you choose, be sure to include lots of lean protein, such as chicken, fish, or lean beef. "Protein contains leucine, an amino acid that seems to protect you from muscle loss during a diet," says Stuart M. Phillips, Ph.D., associate professor of kinesiology at McMaster University in Hamilton, Ontario. Skim milk can help even more: Phillips and his team tracked 56 men who pumped iron five days a week for three months and found that those who downed two cups of fat-free milk soon after their workout built more muscle — and lost more flab — than those who drank soy milk or a flavored-carbohydrate drink. "We have evidence that the benefit is very similar for women," Phillips notes. "They don't put on as much muscle as men, but they lose more fat."

Mistake: Only Doing Cardio

If you never challenge your muscles with strength-training moves, you'll lose up to five pounds of muscle each decade, reports Wayne L. Westcott, Ph.D., fitness research director at the South Shore YMCA in Quincy, MA. Cardiovascular exercise (like walking, biking, swimming, or sweating through an aerobics class) is great for your health, but it isn't strenuous enough to build or even preserve much muscle mass. "Only strength training creates the microscopic tears that prompt muscles to rebuild themselves," explains Phillips. "Lifting weights promotes a continual remodeling of muscle tissue. The process burns a lot of calories."

The Fix: Pump Iron

When women at the South Shore YMCA strength trained for 20 minutes twice a week for 10 weeks, they added 2.6 pounds of calorie-hungry lean muscle and lost 4.6 pounds of body fat, which other research shows is likely to boost metabolic rate by 7 percent, notes Westcott.

You should aim for about 40 to 60 minutes of strength training a week. Use the weight room at your local gym, or exercise with dumbbells or resistance bands at home. If you've never pumped iron before, sign up for a few sessions with a personal trainer. That way, you'll learn how to get the most out of each move — without risking injury. And once you've been at it for a while, you'll need to increase the weight or resistance you're using. "Often, women don't push themselves hard enough because they're afraid they'll bulk up with heavier weights," notes Fernstrom. "But that kind of muscle gain is unlikely because females don't have enough testosterone in their bodies to make muscles like men do."

Mistake: Sticking to the Same Exercises

If you always walk the same route, swim laps at one speed, or even have a single strength-training routine, your muscles adapt and become so efficient that they burn fewer calories while you work out, says Fernstrom. How to tell when it's time for a change? If any of the following is true: You're not sweating as much at the end of your routine; you don't feel that tired after working out; or you're gaining weight even though you aren't eating more or exercising less.

The Fix: Switch It Up

Give your metabolic rate a big boost by adding a few short, fast-paced bursts of speed to your regular walking, biking, swimming, or other aerobic routine. Researchers at the University of Guelph in Ontario found that women who did interval workouts on stationary bikes for two weeks burned 36 percent more fat when they completed a continuous ride afterward. The reason: "More muscle fibers got worked during those high-intensity intervals," says Martin Gibala, Ph.D., an exercise physiologist at McMaster University. "When you push hard in short bursts, it reactivates nerve fibers, builds new capillaries, and forces your body to repair the muscle. All of that burns a tremendous amount of calories — long after you've completed your session."

The best news: "You don't have to be an elite athlete to get the benefits of intervals," explains Gibala. "If you're a walker, pick up the pace for 20 or 30 seconds, then slow down to your usual pace for a minute or two. Then do it again. Start small, with one, two, or three intervals in your walk. As you grow stronger, add more intervals, and make them longer and more intense."

Mistake: Eating Lightly (or Not At All) Before Noon

"Women often have one of two problems with breakfast," says Elisabetta Politi, R.D., nutrition director of the Duke Diet & Fitness Center in Durham, NC. "If they overindulge at night, they don't have much appetite in the morning. Or they're trying to cut calories early in the day, so they don't eat enough in the A.M." Breakfast skimpers and skippers, plus women whose diet resolve is strongest in the morning ("Just coffee and dry toast, please"), commit the same metabolic faux pas: eating too little to flip on their metabolism as well as vital "satisfaction switches" in the brain that register fullness in the stomach.

The Fix: Munch on More Food in the Morning

When researchers at the University of Texas at El Paso analyzed the food diaries of 867 women and men, they discovered a metabolic window of opportunity for appetite control: a hearty breakfast. Study volunteers who ate a bigger meal in the morning went on to eat 100 to 200 fewer calories later in the day. Research from Michigan State University that tracked 4,218 people showed that women who skipped breakfast were 30 percent more likely to be overweight. The best A.M. filler-uppers: oatmeal, eggs, peanut butter — or "anything with fiber and protein," says Politi.

Mistake: Living a High-Stress, Low-Sleep Life

When things get extra-hectic, your levels of cortisol, a stress hormone, shoot up. And that can trigger cravings for high-fat, high-carb foods, report University of California, San Francisco, researchers. The worst part: Your body also sends that extra fat to your waistline. Millions of years ago, this metabolic trick might have helped cavewomen refuel after fending off marauding mastodons. But if you've got 21st-century chronic stress (Job! Kids! House! Marriage!), all that extra cortisol could land you in perpetual "pass the Twinkies" mode.

Sleep deprivation wreaks havoc on your waistline, too. When Harvard Medical School scientists followed 68,183 women for 16 years, they found that those averaging five hours of shut-eye per night were 32 percent more likely to gain 33 pounds than those who got seven hours a night. Those logging an average of six hours per night were 12 percent more likely. What gives? Sleep deprivation increases the appetite-stimulating hormone, ghrelin, and decreases the satisfaction hormone, leptin, say researchers from the University of Chicago. In a study they conducted, tired volunteers craved more candy, cookies, chips, and pasta.

The Fix: Sleep More, Stress Less

Aim for at least seven hours of slumber most nights. Women who snoozed for that long, or longer, had a lower risk of weight problems, the Harvard researchers found. And try meditation — it could keep you in your skinny jeans. A Canadian study of 90 meditators found that those who practiced in a group setting for 1 1/2 hours a week for seven weeks and fit in additional time at home had less stress and anxiety than non-meditators. Or tie on your sneakers and go for a walk in the park or the woods: In a British study, 71 percent of people who walked in the countryside felt less tense afterward. Other research on the health benefits of nature backs this up: A Dutch overview confirmed that just looking at greenery can improve well-being.

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